And then it's Eden's turn to smile a bit – just a tiny, bashful smile – because even though she's just four years old, she knows what's going on around her.

That's pretty normal for most youngsters, but Eden is not like others her age. Despite her smile and her bright, knowing eyes, she does not look as robust as other four-year-olds. Her arms and legs are not as well-developed as those of a child used to running around and playing with other children. She seems to have trouble lifting a cup or even her mom's cell phone, which she uses for playing video games.

Eden has spinal muscular atrophy (SMA), a genetic disease that causes her muscles to deteriorate and wither, robbing her of the strength to do the normal things a child is expected to do. It is a rare disease, occurring in approximately eight out of every 100,000 children born.

Caused by a missing gene that creates a protein vital to motor neurons in the muscles, SMA has no cure. But that isn't stopping Cheslock and other families in Delaware and southern New Jersey from working to find one.

An orphan disease

This Saturday, Jessica Moyer and eight local Zumba instructors will hold a three-hour Zumba event designed to raise funds for SMA research. Eden's struggle against the disease hits Moyer close to home: she and husband Jason Moyer lost their nine-month-old son, Steven, to SMA in June 2002.

She hates the disease and what it has taken from her and so many others. Determined to find a way to beat it, she founded the Delaware/South Jersey chapter of Families of SMA shortly after Steven's death. Today, she and Jason, along with children Isobel, Blaise and Jake, all work to raise more money.

Since 2001, she said the group has raised more than $1.2 million in research funding. And while that's an impressive number, it's not enough.

SMA is an orphan disease, one that's life-threatening but one that does not get as much attention when it comes to paying for research to combat it.

The upcoming Zumbathon Fitness Party, in combination with two other events in May, hopefully will raise another $50,000 for that research effort.

The event will be held beginning at 2 p.m. Saturday, April 13 at the Calvary Community Center. Moyer and the other instructors plan to Zumba the entire three hours, taking only short breaks to award a number of door prizes.

Encouraging research

Like Steven, Eden appeared to be a healthy baby when she was born. Her condition slowly manifested itself, unlike Steven, whose more serious type of SMA did its damage much more rapidly. But by the time she was 10 months old, she'd lost the ability to crawl and could not pull herself up onto her knees. She tired easily, even if just sitting on the floor playing. A genetic blood test at the A.I. DuPont Hospital for Children confirmed the disease.

Since then, Cheslock and her family, which includes husband John and son Pierce, 7, have followed a regular routine in helping Eden fight back. She goes to occupational therapy sessions to hone her fine motor skills and, because she cannot stand on her own, physical therapy to help her stay upright in an effort to fight spinal curvature. Eden also rides horses by lying on the animal's back; the massage-like movement as the horse walks stimulates her muscles in an attempt to slow down their deterioration.

The family has to protect Eden from such mundane things as the common cold. Because she has trouble coughing, she's prone to respiratory infections and pneumonia. Eventually Eden will need surgery to fuse the vertebrae in her spine.

Eden is aware she's different from other children her age, Cheslock says, but she fights back.

"She tries to do things for herself like brushing her teeth or her hair, and she gets mad if I try to help her," she said.

The family is encouraged by recent news that Pfizer pharmaceuticals has begun working with a biotechnology firm to develop include a drug that counters the lack of the specialized protein needed for muscle health. But it is expensive: the national Families with SMA group has helped provide research funding, but the Pfizer experiment has been tagged at $1.4 million.

Still, it is encouraging news. Eden has the same neurologist who treated Steven; in 2001 he had said there was no hope. Today, that doctor sees possibilities not there a decade ago.

Both Cheslock and Moyer encourage people to come out for the event, whether they intend to Zumba or just want to help.

"We have a lot of friends in Zumba and a pretty good following," Moyer said. "It's going to be a lot of fun and it's a great way to raise awareness of SMA."